Corrosion inhibiting compositions and coatings including the same

ABSTRACT

A corrosion inhibiting composition includes a first plurality of carriers and a second plurality of carriers. The first plurality of carriers has a first carrier body which encapsulates a film-forming compound. The second plurality of carriers has a second carrier body encapsulates a corrosion inhibitor. Each of the first and second carrier bodies is formed of a degradable material. Coatings and methods for inhibiting corrosion on a metal substrate are also described herein.

TECHNICAL FIELD

The present disclosure generally relates to corrosion inhibitingcompositions and methods of making and using such compositions, inparticular compositions including film-forming compounds and corrosioninhibitors.

BACKGROUND

Many metals and metal alloys are subject to corrosion that causes thesemetals and metal alloys to lose their structural integrity. As such,methods have been developed to detect the presence of corrosion and toattempt to prevent or inhibit it.

SUMMARY

In one embodiment, a corrosion inhibiting composition includes a firstplurality of carriers and a second plurality of carriers. Each of thefirst plurality of carriers includes a first carrier body and afilm-forming compound. The first carrier body encapsulates thefilm-forming compound. The first carrier body is formed of a firstdegradable material. Each of the second plurality of carriers includes asecond carrier body and first corrosion inhibitor. The second carrierbody encapsulates the first corrosion inhibitor. The first corrosioninhibitor comprises an organic compound including a ring structure. Thesecond carrier body is formed of a second degradable material.

In another embodiment, a corrosion inhibiting composition includes afirst plurality of carriers and a second plurality of carriers. Each ofthe first plurality of carriers includes a first carrier body and afilm-forming compound. The first carrier body encapsulates thefilm-forming compound. The first carrier body is formed of a firstdegradable material. Each of the second plurality of carriers includes asecond carrier body and first corrosion inhibitor. The second carrierbody encapsulates the first corrosion inhibitor. The second carrier bodyis formed of a second degradable material. The first plurality ofcarriers and the second plurality of carriers have different averageouter diameters.

In still another embodiment, a corrosion inhibiting composition includesa first plurality of carriers, a second plurality of carriers, and thirdplurality of carriers. Each of the first plurality of carriers includesa first carrier body and a film-forming compound. The first carrier bodyencapsulates the film-forming compound. The first carrier body is formedof a first degradable material. Each of the second plurality of carriersincludes a second carrier body and first corrosion inhibitor. The secondcarrier body encapsulates the first corrosion inhibitor. The firstcorrosion inhibitor comprises a first organic compound including a ringstructure. The second carrier body is formed of a second degradablematerial. Each of the third plurality of carriers includes a thirdcarrier body and a second corrosion inhibitor. The third carrier bodyencapsulates the second corrosion inhibitor. The second corrosioninhibitor comprises a second organic compound including a ringstructure. The second corrosion inhibitor is different from the firstcorrosion inhibitor. The third carrier body is formed of a thirddegradable material

In yet another embodiment, a coating for inhibiting corrosion on a metalsurface includes a coating base and a corrosion inhibiting composition.The coating base includes an organic layer. The corrosion inhibitingcomposition is dispersed in the coating base. The corrosion inhibitingcomposition includes a first plurality of carriers and a secondplurality of carriers. Each of the first plurality of carriers includesa first carrier body and a film-forming compound. The first carrier bodyencapsulates the film-forming compound. The first carrier body is formedof a first degradable material. Each of the second plurality of carriersincludes a second carrier body and first corrosion inhibitor. The secondcarrier body encapsulates the first corrosion inhibitor. The firstcorrosion inhibitor comprises an organic compound including a ringstructure. The second carrier body is formed of a second degradablematerial.

In yet still another embodiment, a method for inhibiting corrosion on ametal substrate includes applying a coating to a metal substrate. Thecoating includes a coating base and a corrosion inhibiting composition.The coating base includes an organic layer. The corrosion inhibitingcomposition is dispersed in the coating base. The corrosion inhibitingcomposition includes a first plurality of carriers and a secondplurality of carriers. Each of the first plurality of carriers includesa first carrier body and a film-forming compound. The first carrier bodyencapsulates the film-forming compound. The first carrier body is formedof a first degradable material. Each of the second plurality of carriersincludes a second carrier body and first corrosion inhibitor. The secondcarrier body encapsulates the first corrosion inhibitor. The firstcorrosion inhibitor comprises an organic compound including a ringstructure. The second carrier body is formed of a second degradablematerial.

In another embodiment, a corrosion inhibiting composition a firstplurality of carriers and a second plurality of carriers. Each of thefirst plurality of carriers includes a first carrier body and afilm-forming compound. The first carrier body encapsulates thefilm-forming compound. The first carrier body has a first averagediameter and is formed of a first degradable material. Each secondplurality of carriers includes a second carrier body and a corrosioninhibitor. The second carrier body encapsulates the corrosion inhibitor.The second carrier body is formed of a second degradable material andhas an average diameter that is larger than the first average diameter.

In yet another embodiment, a method for inhibiting corrosion on a metalsubstrate includes applying a coating to a metal substrate. The coatingincludes a coating base and a corrosion inhibiting composition. Thecoating base includes an organic matrix. The corrosion inhibitingcomposition is dispersed in the coating base. The corrosion inhibitingcomposition includes a first plurality of carriers and a secondplurality of carriers. Each of the first plurality of carriers includesa first carrier body and a film-forming compound. The first carrier bodyencapsulates the film-forming compound. The first carrier body has afirst average diameter and is formed of a first degradable material.Each second plurality of carriers includes a second carrier body and acorrosion inhibitor. The second carrier body encapsulates the corrosioninhibitor. The second carrier body is formed of a second degradablematerial and has an average diameter that is larger than the firstaverage diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a corrosion inhibiting compositionhaving a plurality of carriers.

FIG. 2 illustrates one embodiment of a carrier having a carrier body anda film-forming compound.

FIG. 3A illustrates one embodiment of a carrier having a carrier bodyand a corrosion inhibitor.

FIG. 3B illustrates another embodiment of a carrier having a carrierbody and a corrosion inhibitor.

FIG. 4 illustrates one embodiment of two carriers, one having afilm-forming compound and the other carrier having a corrosioninhibitor.

FIG. 5 illustrates one embodiment of a plurality of carriers, one havinga film-forming compound and the other carriers having differentcorrosion inhibitors.

FIG. 6 illustrates an embodiment of a coating system applied to asurface of a metal body portion of a vehicle.

FIG. 7 illustrates the Adhesion Test procedure used to measure the creepvalue of a test piece (e.g., metal substrate).

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown, byway of illustration, specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention. Otherembodiments may be utilized and structural, logical, and chemicalchanges may be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the present invention isdefined only by the appended claims and equivalents thereof.

FIG. 1 generally illustrates a corrosion inhibiting composition 10. Thecorrosion inhibiting composition 10 can be applied to a metal surfacehas indicated in FIG. 5), such as a vehicle body. As shown in FIG. 1,the composition 10 can include a plurality of carriers 15.

In general, each carrier 15 can be a microparticle or microcapsule thatcan be included in a protective coating. Such protective coating canthen be applied to a metal substrate and cured thereon, so that anymechanical damage or corrosive damage to the resultant coating can causethe carrier to rupture or otherwise fail so that a repair or protectivesubstance is released and deployed into or onto the damaged area of thecoating, for example, to the exposed surface of a metal substrate. In anon-limiting example, the carrier 15 can have a substantially sphericalconfiguration. It will be appreciated that such carriers 15 can formspherical particles, including but not limited to, microspheres,microcapsules, microparticles, nanospheres, nanocapsules andnanoparticles. However, the carrier is not limited to sphericalparticles, as one of ordinary skill in the art will appreciate that avariety of different shapes may be used for the carrier. Illustrativeexamples include, rods, fibers, tubes or elongated capsules.

FIGS. 2, 3A and 3B are enlarged, non-limiting, views of carrier 15. Asshown in FIG. 2, carrier 15 can include a carrier body 17 and at leastone film-forming compound 21. As shown in FIGS. 3A and 3B, carrier 15can include a carrier body 17 and at least one organic corrosioninhibitor 20. As shown in FIG. 2, the carrier 15 is in the form of amicrocapsule such that the carrier body 17 encircles and encapsulatesthe least one film-forming compound 21 therein. The film-formingcompound 21 can be a liquid, solid, or a gas entrapped in aerogel orvarious combinations thereof. For certain embodiments, a film-formingcompound is dissolved or dispersed in a hydrophobic substance, such asoil, or a hydrophilic substance, such as water, optionally with one ormore active substances such as a corrosion inhibitor. For certainembodiments, the carrier 15 can contain only active substances such asfilm forming compounds 21 and organic corrosion inhibitors 20 (see FIGS.3A and 3B).

In certain embodiments, the carrier body 17 of the carrier 15 cancomprise gelatin, polyurethane, urea formaldehyde, melamineformaldehyde, melamine formaldehyde/pentaerythritol tetrakis or asuitable combination thereof. In certain embodiments, the carrier body17 can be formed having a multi-walled shell.

Each carrier can have a substantially spherical shape with an averageouter diameter up to 50 μm. In certain embodiments, each carrier has anaverage outer diameter ranging from about 100 nm to 15 μm. In certainembodiments, each carrier has an average outer diameter ranging fromabout 0.5 μm to 10 μm. In certain embodiments, each carrier has anaverage outer diameter of about 5 μm or less. In certain embodiments,each carrier has an average outer diameter ranging from about 1 μm to 2μm. The average outer diameter of each carrier can be measured using avariety of suitable techniques, including for example, opticalmicroscopy and laser diffraction.

For carriers encapsulating a film-forming compound, such carriers canhave an average diameter larger than the average diameter of a carrierencapsulating a corrosion inhibitor. In certain embodiments, a carriercomprising a film-forming compound can have an average diameter fromabout 3 microns to about 15 microns; in certain embodiments from about 5microns to about 10 microns; and in certain embodiments from about 6microns to about 8 microns. In certain embodiments, a carrier comprisinga corrosion inhibitor can have an average diameter up to about 5microns; in certain embodiments up to about 3 microns; and in certainembodiments from about 0.5 micron to about 2 microns.

Each carrier 15 can having a carrier body 17 formed from a degradablematerial. For example, the mechanical integrity of the carrier body 17can break down, disintegrate or otherwise deteriorate in the presence ofa base (or an alkaline), e.g., having a pH of about 8 or above, suchthat the carrier body 17 is breached and the film-forming compound 21 isreleased from the carrier 15. In certain embodiments, the carrier body17 can be breached due to mechanical damage to the carrier body 17(e.g., rupture, fracture, scratching, etc.). It will be appreciated thatcarrier body 17 for each carrier 15 can be formed from differentdegradable materials. It will also be appreciated that once the carrierbody 17 degrades; the film-forming compound 21 can be released to theenvironment adjacent to the carrier 15.

Carriers 15 having carrier bodies 17 that break down under basic, oralkaline, conditions or rupture due to mechanical damage are generallyknown in the art. It is the interaction of alkaline conditions withfunctional groups of the cross-linking agent that causes carrier body 17to break down or disintegrate under alkaline conditions. Alternatively,the film-forming compound 21 can be released mechanically, such as byscratching or applying pressure to the carrier body 17 of the carriers15 in the corrosion inhibiting composition 10 or to a coating to whichthe corrosion inhibiting composition 10 is applied.

A basic, or alkaline, condition often forms in the presence of corrosionin a metal or a metal alloy, e.g., a basic condition often forms next tocorrosion-induced pits, crevices, etc. For example, when a drop of saltwater is applied to steel, an anodic reaction can occur to produce arust spot, and a cathodic reaction (the reduction reaction of the oxygenin the presence of water), can occur to produce a basic condition.Therefore, when a coating, containing the corrosion inhibitingcomposition 10, is applied to a metal substrate, and if corrosionoccurs, carrier bodies 17 of the plurality of carriers 15 can be exposedto the basic condition (e.g., alkaline) and will break down ordisintegrate under the basic condition resulting from the corrosion,thereby releasing film-forming compounds 21. Corrosion can include anychemical or electrochemical process involving the deterioration ordegradation of metals, including pitting, crevice corrosion, dissimilarmetal corrosion, or the like.

An acidic condition often forms in the presence of corrosion in a metalor a metal alloy, e.g., an acidic condition often forms atcorrosion-induced pits, crevices, etc. For example, when a drop of saltwater is applied to steel, an anodic reaction can occur to produce anacidic condition, and a cathodic reaction (the reduction reaction of theoxygen in the presence of water), can occur to produce a basiccondition. Therefore, when a coating, containing the corrosioninhibiting composition 10, is applied to a metal substrate, and ifcorrosion occurs, carrier bodies 17 of the plurality of carriers 15 canbe exposed to the acidic condition and will break down or disintegrateunder the acidic condition resulting from the corrosion, therebyreleasing film-forming compounds 21. Corrosion can include any chemicalor electrochemical process involving the deterioration or degradation ofmetals, including pitting, crevice corrosion, dissimilar metalcorrosion, or the like. In a non-limiting example, both a mixture ofalkaline and acidic degradable polymer carriers 15 can be used. It is tobe understood that the same corrosion inhibitor can be used in bothtypes of carriers or different corrosion inhibitors can be used in anacidic degradable carrier and alkaline degradable carrier.

Microcapsules as described above can be formed using a variety ofsuitable methods. For example, a microcapsule can be formed by formingan oil (e.g., toluene, vegetable oil) in water emulsion. A surfactant,such as xanthan gum, Attagel 40 (available from Engelhard Corporation,Iselin, N.J., USA), Petro BAF (available from Akzo Nobel Chemicals,Inc., Chicago, Ill., USA), and/or Reax 83 (available from MeadWestvacoCorporation, Stamford, Conn., USA) can be added to the emulsion toevenly distribute the oil in the water. A pre-polymer (e.g., an aminoresin pre-polymer), a cross-linking agent having one or more ester orthioester groups that are broken down under alkaline conditions, and theorganic corrosion inhibitor 20 can then be added to the oil phase. Acatalyst (e.g., an inorganic acid) can be added to the water phase. Theoil in water emulsion can then be heated, causing a polymerizationreaction to occur at the water-oil interface, thus allowing for theformation of the carrier body 17 around film-forming compound 21 to formthe carrier 15.

In a non-limiting example shown in FIG. 3A, the carrier 15 can be amicroparticle including the organic corrosion inhibitor 20, andoptionally one or more other active ingredients. As shown in FIG. 3A,the carrier body 17 of the carrier 15 can be a solid binder thatcontains (e.g., encapsulates) the organic corrosion inhibitor 20. Theorganic corrosion inhibitor 20 can be a liquid, solid, or a gasentrapped in aerogel or various combinations thereof. For certainembodiments, the organic corrosion inhibitor 20 can be dissolved ordispersed in a hydrophobic substance, such as oil, or a hydrophilicsubstance, such as water, and optionally one or more active substancessuch as corrosion indicator, inorganic corrosion inhibitor, film-formingcompound, or various combinations thereof. For certain embodiments, thecarrier 15 contains only active substances such as the organic corrosioninhibitor 20, and optionally corrosion indicators, film-formingcompounds, or various combinations thereof.

The solid binder forming the carrier body 17 of the microparticlecarrier 15 as shown in FIG. 3A, can comprise gelatin, polyurethane, ureaformaldehyde, melamine formaldehyde, melamineformaldehyde/pentaerythritol tetrakis or a suitable combination thereof.

The microparticle carrier 15 shown in FIG. 3A can include a carrier body17 comprising a solid binder formed from a degradable material. Forexample, the mechanical integrity of the solid binder can break down,disintegrate or otherwise deteriorate in the presence of a base (or analkaline), e.g., having a pH of about 8 or above, such that the solidbinder is breached and the organic corrosion inhibitor 20 is releasedfrom the carrier 15. In certain embodiments, a solid binder can bebreached due to mechanical damage to the solid binder (e.g., rupture,fracture, scratching, etc.). It will be appreciated that the solidbinder for each carrier body 17 of each carrier 15 can be formed fromdifferent degradable materials. It will also be appreciated that once asolid binder degrades the organic corrosion inhibitor 20 can besubsequently released to the environment adjacent to the carrier 15.

Microparticle type carriers 15 having carrier body 17 formed of a solidbinder that breaks down under basic, or alkaline, conditions or rupturedue to mechanical damage are known in the art. Such microparticles canbe formed using a variety of suitable methods. A basic, or alkaline,condition often forms in the presence of corrosion in a metal or a metalalloy, e.g., a basic condition often forms next to corrosion-inducedpits, crevices, etc. For example, when a drop of salt water is appliedto steel, an anodic reaction can occur to produce a rust spot, and acathodic reaction (the reduction reaction of the oxygen in the presenceof water), can occur to produce a basic condition. Therefore, when acoating, including the corrosion inhibiting composition 10, is appliedto a metal substrate, and if corrosion occurs, the solid binders formingthe carrier bodies 17 of the microparticle carriers 15 can be exposed tothe basic condition (e.g., alkaline) and will break down or disintegrateunder the basic condition resulting from the corrosion, therebyreleasing the organic corrosion inhibitor 20. Corrosion can include anychemical or electrochemical process involving the deterioration ordegradation of metals, including pitting, crevice corrosion, dissimilarmetal corrosion, or the like.

In a non-limiting example shown in FIG. 3B, the carrier 15 can be apolymer particle (e.g., a polymer microparticle and a polymernanoparticle) including the organic corrosion inhibitor 20, andoptionally one or more other active ingredients. As shown in FIG. 2C,the carrier body 17 of the carrier 15 can be at least one polymer chainthat contains (e.g., encapsulates) the organic corrosion inhibitor 20.In one embodiment, the carrier body 17 can be formed of a high pHresponsive polymer (HPRP). The HPRP can have a number average molecularweight of about 2,500 to about 5,000. The organic corrosion inhibitor 20can be a liquid, solid, or a gas entrapped in aerogel or variouscombinations thereof. For certain embodiments, the organic corrosioninhibitor 20 can be dissolved or dispersed in a hydrophobic substance,such as oil, or a hydrophilic substance, such as water, and optionallyone or more active substances such as corrosion indicator, inorganiccorrosion inhibitor, film-forming compound, or various combinationsthereof. For certain embodiments, the carrier 15 contains only activesubstances such as the organic corrosion inhibitor 20, and optionallycorrosion indicators, film-forming compounds, or various combinationsthereof.

The polymer particle carrier 15 shown in FIG. 3B can include a carrierbody 17 comprising at least one polymer chain (e.g., HPRP withcarboxylic acid end groups and a hydrophilic segment) formed from adegradable material. For example, the mechanical integrity of thepolymer chain(s) can break down, disintegrate or otherwise deterioratein the presence of a base (or an alkaline), e.g., having a pH of about 8or above, such that the solid binder is breached and the organiccorrosion inhibitor 20 is released from the carrier 15. It will beappreciated that the polymer chain(s) for each carrier body 17 of eachcarrier 15 can be formed from different degradable materials. It willalso be appreciated that once a polymer chain degrades (e.g., breaksapart) the organic corrosion inhibitor 20 can be subsequently releasedto the environment adjacent to the carrier 15.

Polymer particle type carriers 15 having carrier body 17 formed of apolymer chain that breaks down under basic, or alkaline, conditions orrupture due to mechanical damage are known in the art. Such polymerparticles can be formed using a variety of suitable methods, including,for example, a phase inversion method. For example, the organiccorrosion inhibitor 20 can be dispersed between the entangled polymerchains that form the carrier body 17. A basic, or alkaline, conditionoften forms in the presence of corrosion in a metal or a metal alloy,e.g., a basic condition often forms next to corrosion-induced pits,crevices, etc. For example, when a drop of salt water is applied tosteel, an anodic reaction can occur to produce a rust spot, and acathodic reaction (the reduction reaction of the oxygen in the presenceof water), can occur to produce a basic condition. Therefore, when acoating, including the corrosion inhibiting composition 10, is appliedto a metal substrate, and if corrosion occurs, the polymer chainsforming the carrier bodies 17 of the carriers 15 can be exposed to thebasic condition (e.g., alkaline) and will break down or disintegrateunder the basic condition resulting from the corrosion, therebyreleasing the organic corrosion inhibitor 20. Corrosion can include anychemical or electrochemical process involving the deterioration ordegradation of metals, including pitting, crevice corrosion, dissimilarmetal corrosion, or the like.

In certain embodiments, an organic corrosion inhibitor can comprise fromabout 15% to about 50%, by weight, of a carrier; in certain embodiments,from about 20% to about 40% by weight, of a carrier; and in certainembodiments from about 20% to about 35%, by weight, of a carrier.

Once the carrier body 17 of the carrier 15, including any of thoseillustrated in FIGS. 2, 3A or 3B, has degraded, a repair substanceand/or an anti-corrosion substance can be released.

Repair substances, such as film-forming compounds can fill voids in theoriginal coating to seal and protect the damaged area. Thesefilm-forming compounds can be released from carriers (e.g.,microcapsules or microparticles) once the encapsulant (e.g., carrierbody) becomes damaged. Such suitable film-forming compounds can includea clear varnish (e.g., an acrylic varnish), epoxy resins, polar aproticsolvents, siloxane resins (e.g., polydimethylsiloxane), linseed oil,tung oil, silyl ester, iscocyanates, or combinations thereof. Othersuitable film-forming compounds can include polybutenes, phenolics,phenolic varnishes, long chain polyester diluents, carrier diluents, andcombinations thereof. Other suitable film-forming compounds are furtherdescribed in U.S. Patent Application Publication Nos. 2006/0042504,2008/0152815, 2012/0000810 and 2012/0052307.

Without being limited to any particular theory, an organic corrosioninhibitor can use one or more mechanisms to provide the requisitecorrosion protection, including for example, absorption and adsorption.Organic corrosion inhibitors can include, but are not limited to, organophosphonates (including, but not limited to phenyl phosphonic acid),amine compounds (including, but not limited to triethanolamine anddodecylamine), imadazole compounds (including, but not limited tobenzoimidazole, and 2-phenilimidazoline), oxazole compounds, indazolecompounds, triazole compounds (including, but not limited tobenzotriazole), pyrazole compounds (including, but not limited to3-Methyl-5-pyrazolone), thiazole compounds (including, but not limitedto 2-Mercaptobenzothiazole), quinoline and quinolone compounds(including, but not limited to 8-Hydroxyquinoline, and8-Hydroxyquinaldine), their derivatives, and combinations thereof.Certain corrosion inhibitors are also described in U.S. patentapplication Ser. No. 13/839,895, filed Mar. 15, 2013, which is herebyincorporated herein by reference in its entirety.

In certain embodiments, as illustrated in FIG. 4, a corrosion inhibitingcomposition can include a first carrier 15 a and a second carrier 15 b.The first carrier 15 a can include a first carrier body 17 a and afilm-forming compound 21. The first carrier 15 a can be formed from amicrocapsule. The second carrier 15 b can include a second carrier body17 a and a corrosion inhibitor 20 b. The second carrier 15 b can beformed from a microparticle.

In certain embodiments, a corrosion inhibiting composition can include aplurality of carriers, each having a carrier body and a corrosioninhibitor encapsulated by the carrier body. The corrosion inhibitor caninclude an organic compound including a ring structure. The carrier bodycan be formed of a degradable material. In a non-limiting example, thecorrosion inhibitor can be a chelating agent or capable of acting as achelating agent. For example, the corrosion inhibitor may have aplurality of donor atoms. In a non-limiting example, the corrosioninhibitor can include an organic compound such as a heterocycliccompound with an endocyclic donor atom and an exocyclic donor atom. Forexample, the corrosion inhibitor may include a heterocyclic compoundwith an exocyclic donor atom directly bonded to the heterocycliccompound (e.g., 2-Mercaptobenzothiazole and 3-Methyl-5-pyrazolone), oran exocyclic donor atom that is not directly bonded to the heterocyclicring (e.g., 8-Hydroxyquinoline and 8-Hydroxyquinaldine). In anon-limiting example, the carrier body can comprise gelatin,polyurethane, urea formaldehyde, melamine formaldehyde/pentaerythritoltetrakis or a suitable combination thereof. In certain embodiments, theplurality of carriers can form microparticles.

In an embodiment shown in FIG. 4, the corrosion inhibiting composition10 can include a first carrier 15 a having a film-forming compound 21, asecond carrier 15 b including a first corrosion inhibitor 20 b, and athird carrier 15 c including a second corrosion inhibitor 20 c that isdifferent from the first corrosion inhibitor 20 b. In certainembodiments, the corrosion inhibiting composition 10 will comprise afirst plurality of carriers 15 a and a second plurality of carriers 15b, and optionally a third plurality of carriers 15 c.

As generally represented by FIG. 4, the second carrier 15 b can includethe first corrosion inhibitor 20 b that is an organo phosphonate, andthe third carrier 15 b can include the second corrosion inhibitor 20 cthat is an organic compound including a ring structure. In a nonlimiting example, the organo phosphonate can be a phosphonic acidderivative (e.g., phenyl phosphonic acid). In a non-limiting example,the second corrosion inhibitor can be a chelating agent or be capable ofacting as a chelating agent. For example, the second corrosion inhibitormay have a plurality of donor atoms. In a non-limiting example, thesecond corrosion inhibitor 20 c can include a heterocyclic compound withan endocyclic donor atom and an exocyclic donor atom. For example, thesecond corrosion inhibitor 20 c may include a heterocyclic compound withan exocyclic donor atom directly bonded to the heterocyclic ring (e.g.,2-Mercaptobenzothiazole and 3-Methyl-5-pyrazolone), or an exocyclicdonor atom that is not directly bonded to the heterocyclic ring (e.g.,8-Hydroxyquinoline and 8-Hydroxyquinaldine).

In one non-limiting example, the first corrosion inhibitor can be phenylphosphonic acid, and the second corrosion inhibitor can be2-Mercaptobenzothiazole. In another non-limiting example, the firstcorrosion inhibitor can be phenyl phosphonic acid, and the secondcorrosion inhibitor can be 8-Hydroxyquinoline.

In certain embodiments, the corrosion inhibiting composition 10 of FIG.4 can include a second carrier 15 b including a first organic corrosioninhibitor 20 b, and a third carrier 15 c including a second organiccorrosion inhibitor 20 c that is different from the first organiccorrosion inhibitor 20 b. The second carrier 15 b and the third carrier15 c may be formed as microparticles that are degradable in a corrosiveenvironment. For example, a first carrier body 17 a, a second carrierbody 17 b and a third carrier body 17 c of the respective first carrier15 a, the second carrier 15 b and the third carrier 15 c can be formedof degradable materials. It will be appreciated that the first carrierbody 17 a, the second carrier body 17 b, and the third carrier body 17 ccan be formed of the same or different materials. In a non-limitingexample, the first corrosion inhibitor 20 b and the second corrosioninhibitor 20 c can be chelating agents or capable of acting as chelatingagents. In a non-limiting example, the first corrosion inhibitor 20 bcan be an organic compound including a ring structure, and the secondcorrosion inhibitor 20 c can be an organic compound including a ringstructure. For example, the first corrosion inhibitor 20 b and thesecond corrosion inhibitor can 20 c each have a plurality of donoratoms. In a non-limiting example, one or both of the corrosioninhibitors 20 b, 20 c can include(s) a heterocyclic compound with anendocyclic donor atom and an exocyclic donor atom. In a non-limitingexample, the first corrosion inhibitor 20 b can include a heterocycliccompound with an exocyclic donor atom directly bonded to theheterocyclic compound (including, but not limited to2-Mercaptobenzothiazole and 3-Methyl-5-pyrazolone), and the secondcorrosion inhibitor can include an exocyclic donor atom that is notdirectly bonded to the heterocyclic compound (including, but not limitedto 8-Hydroxyquinoline and 8-Hydroxyquinaldine).

In a non-limiting example, a first organic corrosion inhibitor can be8-hydroxyquinoline (structure shown below) or a derivative thereof,8-hydroxyquinaldine or a derivative thereof or any combination thereof.8-hydroxyquinoline is a bidentate binding unit containing both an oxygendonor atom (exocyclic donor), and a nitrogen donor atom (endocyclicdonor). 8-hydroxyquinoline is capable of acting as a chelating agent andmay have the structure shown below when bound to a metal atom, M.

The second organic corrosion inhibitor can be 2-mercaptohenzothiazole ora derivative thereof, 2-mercaptobenzimidazole or a derivative thereof,2-(benzothiazol-2-ylsulfanyl)-succinic acid or a derivative thereof, ora combination thereof. 2-mercaptobenzothiazole is a bidentate bindingunit containing both a sulfur donor atom (exocyclic donor), and anitrogen donor atom (endocyclic donor).

A variety of methods are known for forming the carrier 15, such asmicrocapsules and microparticles.

In certain embodiments, hydrophilic-core microcapsules, such aswater-core microcapsules, can be formed from emulsions havinghydrophilic-phase droplets dispersed in a hydrophobic substance. Oneexample is water-in-oil emulsions. Water-in-oil emulsions includehydrophilic-phase droplets (e.g., as the dispersed phase) dispersed inthe hydrophobic phase (e.g., as the continuous phase). If a compound(active substance) is hydrophilic, or it can be dissolved or dispersedin a hydrophilic solvent (e.g. water), then it can be possible toencapsulate it in hydrophilic-core microcapsules. When a compound doesnot have sufficient solubility in the hydrophilic solvent, a co-solventcan be used to improve the dissolution of the compound and to facilitatethe encapsulation process. Similarly, when a compound cannot bedispersed into the hydrophilic phase to form a reasonably stablesuspension (e.g., indicated by droplets of the compound being dispersedthroughout the hydrophilic phase and the compound remaining dispersedduring emulsion formation and encapsulation processes), a surfactant canbe used to improve the dispersion of the compound and facilitate theencapsulation process. So if a compound can be dissolved or dispersed ina hydrophilic solvent, with or without the aid of a co-solvent or asurfactant, it is possible to encapsulate it into hydrophilic-coremicrocapsules.

Hydrophilic-core microcapsules are typically used for encapsulatingwater-soluble materials, but not oil-soluble materials, such asnon-polar molecules. Oil-soluble materials can be incorporated intohydrophilic-core microcapsules by first adding them to a co-solvent, andthen adding the resulting solution to the hydrophilic phase.Alternatively, a surfactant can be added to the hydrophilic phase. Thiswill dissolve or disperse the non-polar or oil-soluble reagents into thehydrophilic phase. The emulsion (e.g. water-in-oil emulsion) can then beformed by adding the hydrophilic phase to a hydrophobic phase and areaction can be initiated to encapsulate the oil, with the activesubstance dissolved or dispersed therein, into the core of thehydrophilic-core microcapsules.

In general, oil-core as well as water-core microcapsules can formed toinclude a film-forming compound 21 within the core, being encapsulatedby a carrier body 17, such as by a polymeric shell (e.g., see FIG. 2).Alternatively, the film-forming compound 21 in an oil-core microcapsulecan be dissolved or dispersed in a hydrophobic substance, such as oil,with or without the aid of a co-solvent or a surfactant. Thefilm-forming compound 21, of a water-core microcapsule, can be dissolvedor dispersed in water, with or without the aid of a co-solvent or theaid of a surfactant. Other active ingredients including, but not limitedto, a dye, a corrosion indicator, an inorganic corrosion inhibitor, afilm-forming compound, or various combinations thereof may be includedwithin the carrier body 17.

The polymeric shell or solid binder of either oil-core or water-coremicrocapsules or microparticles can include a polymer formed from anencapsulant-forming compound (e.g., precursor) that can include across-linking agent having one or more ester and mercapto groups and/ora film-forming pre-polymer. In certain embodiments, anencapsulant-forming compound can include about 5 to about 75 percent(e.g., about 20 to about 50 percent) by weight of a cross-linking agentand about 25 to about 95 percent (e.g., about 50 to about 80 percent) byweight of a film-forming pre-polymer. Examples of the cross-linkingagent include, but are not limited to, pentaerythritoltetrakis(2-mercaptoacetate) or compounds with similar structure (e.g.,pentaerythritol tetrakis(3-mercaptopropionate) (PTT), pentaerythritol,dipentaerythritol, dipentaerythritol pentaacrylatetetra(mercaptoacetate), pentaerythritol tetra(acrylate), and theirderivatives. As described herein, examples of the film-formingpre-polymer can include, but are not limited to, urea formaldehydepre-polymer resin (e.g., butylated urea-formaldehyde resin, such asCYMEL® U80), melamine formaldehyde resin, polyurethane pre-polymers,polyols, or film-forming monomers, such as urea and formaldehydesolution, melamine and formaldehyde solution, isocyanates and variousglycols, etc. The encapsulant-forming compound can form the shells ofthe oil-core as well as the water-core microcapsules, or the solidbinders of microparticles as described herein.

The microcapsule shell of either oil-core or water-core microcapsulescan include one or more chemical bonds due to the ester group in thecross-linking agent that are cleavable (e.g., broken down) at ambienttemperature when the surrounding pH changes due to the occurrence of acorrosion process. For example, the ester groups can undergo anirreversible hydrolysis reaction under basic pH, e.g., when exposed toan alkali.

Cross-linking agents that have three or four functional groups, such aspentaerythritol tetrakis(2-mercaptoacetate), penta erythritoltetrakis(3-mercaptopropionate) (PTT), pentaerythritol,dipentaerythritol, dipentaerythritol pentaacrylatetetra(mercaptoacetate), and pentaerythritol tetraacrylate can alsoprovide chemical resistance (e.g. solvent resistance) to themicrocapsule shells.

It will be appreciated that a number of suitable techniques areavailable to form the microcapsules and microparticles as describedherein, including those methods further described in U.S. Pat. Nos.7,569,625, 7,790,225 and U.S. Patent Application Publication Nos.2010/0320421, 2010/0305234, 2012/0207921 and 2013/0017612.

In certain embodiments, corrosion inhibitors once released fromrespective carriers (e.g., microparticles/microcapsules) can adhere orattach to an exposed surface of a metal substrate (e.g., steel door ofan automobile) to provide an anti-corrosion barrier. In certainembodiments, such organic corrosion inhibitors can be absorbed oradsorbed into the surface of the metal substrate providing effectivecorrosion resistance. In certain embodiments, corrosion inhibitingcompositions described herein can also be added to a coating base toform a protective coating which can be applied to these metalsubstrates.

As shown in FIG. 6, surface 26 of a metal substrate 30 is shown overlaidwith multiple layers of coatings 12, 14, 16 and 18 (e.g., paints),collectively indicated as 40, with layer 18, immediately adjacent to thesurface 26 of a metal substrate 30, incorporating carriers 15 comprisingeither film-forming compounds 21 or corrosion inhibitors 20. Metalsubstrate 30 can, for example, be an outer door panel of a vehicle(e.g., automobile). For coating systems, self-healing or protectivecoatings can be fabricated by adding carriers containing at least one“self-healing” compound (including, for example, corrosion inhibitors)to commercially available paint primers. Paint primers can includecathodic electrodeposition coatings. Such carriers can release theself-healing compound or compounds when the coating system is damaged.Such damage can occur when the coating is mechanically damaged orsuffers corrosive damage.

Coatings, like paint, can include a mixture of solids and a suitablebinder, possibly also incorporating a solvent, which can generally beapplied to a surface as a thin liquid layer and forms a closely adherentcoating on the surface when the liquid layer is “cured”. Paintformulations vary widely. For example, a solvent can be an organicliquid, or water or can be eliminated entirely by applying the paintsolids in powder form, relying on electrostatic attraction to build athin layer. Many automotive paints employ water as a solvent and arereferred to as “water-based”. Irrespective of the solvent however, inone example, automotive paints can be cured by exposure to heat in apaint bake oven.

Automotive coatings 40 can include a single layer or comprise multiplelayers (e.g., four layers represented as layers 12, 14, 16 and 18 inFIG. 4). In general, layer 18 immediately adjacent to surface 26 of ametal substrate 30 can be generally intended to provide corrosionprotection once the automotive coatings 40 have suffered damage. Onemethod of applying layer 18 can be via electrodeposition (or e-coating),but it will be appreciated by one skilled in the art, that a variety ofother suitable coating techniques to apply layer 18 can be employed(e.g., spraying, brushing, rolling, etc.). Subsequent layers caninclude: a primer-surfacer, such as represented by 16, to smooth outsurface irregularities, improve stone-chip performance, and help protectagainst visible and UV light; a basecoat, such as represented by 14, toprovide color and aesthetic effects; and a clearcoat, such asrepresented by 12, to provide primary protection against environmentaleffects and imparts gloss and depth to the overall paint finish. Thesethree coatings can be applied as liquid sprays. All three coatings canbe applied without intermediate high temperature exposure or cure, aprocedure commonly described as ‘wet on wet’, and cured in a singlepaint bake oven. However, layer 18 can be cured separately in a separatepaint bake oven prior to applying the remaining layers. Thus, typicalautomobile painting practice will expose painted parts to the elevatedtemperatures required for paint baking at least twice. However, it willbe appreciated that there are a variety of suitable methods andtechniques of applying coatings (e.g., paint layers) to surfaces of ametal body part of a vehicle.

The coating of layer 18 can include a coating base 19 and one or moreadditives such as a plurality of carriers 15 (e.g., microcapsules andmicroparticles). The coating base 19 can be a solvent, such as analiphatic hydrocarbon (e.g., aliphatic petroleum distillates). Othersuch coating bases 19 (e.g., paint primers) can include greases,lubricants, varnishes, lacquers, shellacs, waxes, polishes,polyurethanes, oil-based enamels, enamel undercoater, latex acrylics,acrylic-based formulations, epoxy-based formulations (e.g., epoxyisocyanate resins), and other suitable combinations thereof. Othersuitable coating bases are described in U.S. Pat. Nos. 5,070,174,7,612,152 and 7,723,405. Carriers 15 can be dispersed into a coatingbase 19 using a variety of suitable techniques (e.g., by mixing,chemical dispersion agents, etc.). Suitable methods of dispersingmicrocapsules into a coating base are described in U.S. PatentApplication Publication No. 2011/0064941. A coating can comprise about0.1% by weight or more of carriers. In certain embodiments, a coatingcan comprise about 0.5% by weight or more of carriers; in certainembodiments, about 1.0% by weight or more of carriers; in certainembodiments, about 2.5% by weight or more of carriers; in certainembodiments, about 5.0% by weight or more of carriers; in certainembodiments, about 7.5% by weight or more of carriers; and in certainembodiments, about 10% by weight or more of carriers. It will beunderstood that a coating can include materials or substances inaddition to the coating base and carriers. For example, a coating caninclude one or more agents that facilitate improvements in theproperties of the coating, or a coating can include a filler to increasethe volume or mechanical integrity of the coating.

In certain embodiments, a coating base can include a copolymer thatincludes an epoxy-group, such as an epoxy resin. Epoxy-groups can have amolecular weight of about 100 or more; in certain embodiments, of about500 or more; in certain embodiments, of about 750 or more; in certainembodiments, of about 1,000 or more; in certain embodiments, of about1,250 or more; in certain embodiments, of about 1,500 or more; and incertain embodiments of about 2,000 or more. Epoxy-groups can have amolecular weight of about 100,000 or less; in certain embodiments, ofabout 50,000 or less; in certain embodiments, of about 20,000 or less;in certain embodiments, of about 15,000 or less; in certain embodiments,of about 10,000 or less; in certain embodiments, of about 7,500 or less;in certain embodiments, of about 5,000 or less; and in certainembodiments of about 4,000 or less. It will be appreciated that a numberof techniques are known to calculate the molecular weight of suitableepoxy-groups and copolymers.

A coating base can include the dry portion of a coating which does notinclude the carriers. A coating can comprise about 75% by weight or moreof a coating base. In certain embodiments, a coating can comprise about80% by weight or more of a coating base; in certain embodiments, about85% by weight or more of a coating base; in certain embodiments, about90% by weight or more of a coating base; in certain embodiments, about95% by weight or more of a coating base; in certain embodiments, about97.5% by weight or more of a coating base; in certain embodiments, about99% by weight or more of a coating base; in certain embodiments, about99.5% by weight or more of a coating base; and in certain embodiments,about 99.9% by weight or more of a coating base.

A coating can have a thickness of about 5 μm or more; in certainembodiments, of about 10 μm or more; in certain embodiments, of about 15μm or more; in certain embodiments, of about 25 μm or more; in certainembodiments, of about 50 μm or more; in certain embodiments, of about100 μm or more; in certain embodiments, of about 150 μm or more; incertain embodiments of about 200 μm or more; and in certain embodimentsof about 300 μm or more. In certain embodiments, a coating can have athickness of about 10 μm to about 100 μm. In certain embodiments, acoating can have a thickness of about 5 μm to about 25 μm.

To assist in locating corrosive damage to a coating, corrosionindicators can also be included as an encapsulate in a carrier. Suitablecorrosion indicators can include a pH indicator that changes color overthe alkaline region (e.g., pHs above about 8), such as phenolphthalein.Other suitable corrosion indicators can include ones that fluoresce,such as 7-hydroxycoumarin or coumarin, in the presence of or upon theoxidation of a metal or in the presence or upon the formation of a metalcation complex.

In certain embodiments, where a coating is applied, carriers can includeone or more film-forming compounds, corrosion inhibitors, corrosionindicators, or various combinations thereof. For certain embodiments, ifa coating is exposed to trauma that carriers to break or rupture, afilm-forming compound in the carrier can be released to cover at least aportion of the surface area suffering the trauma and then acts to reducethe degree of any exposed metal of corroding. For certain embodiments, acorrosion inhibitor in a carrier can also be released to act to furtherreduce the degree of corrosion of any exposed metal.

Note that if corrosion occurs at locations away from the trauma locationdue to small breaks in the coating, such as chips, or other coatingdefects, corrosion inhibitors and film-forming compounds can be releaseddue to encapsulants breaking down in the presence of the basiccondition, resulting from the corrosion.

In certain embodiments, a portion of carriers in a coating can containcorrosion inhibitors and another portion of carriers in the coating cancontain film-forming compounds. In certain embodiments, a portion ofcarriers in a coating can contain corrosion inhibitors, another portionof carriers in the coating can contain film-forming compounds, and yetanother portion of carriers in the coating can contain corrosionindicators. For certain embodiments, carriers having different contentsare randomly distributed within a coating base so that carriers havingthe different functions of indicating, inhibiting, and/or film-formingcan be adjacent each other, as well as carriers having like functionsbeing adjacent to each other. For certain embodiments, the differentfunctions of encapsulates can be incorporated into a coating byencapsulating different encapsulates into the same carriers.

In an embodiment, the corrosion inhibiting composition 10 may be appliedin an organic matrix between two substrates. In a non-limiting example,the organic matrix may be an adhesive. In a non-limiting example, thesubstrates may be different metals or metal alloys such as aluminum andsteel. In another non-limiting example, one substrate may be a metal ormetal alloy and the other substrate may be a polymeric substrate. Thepolymeric substrate may include fiber reinforcements.

Procedures

A. Hot Salt Water Test

The hot salt water test can measure the amount of corrosion suffered bya metal substrate by measuring the amount of creep that occurs at thetested area.

To measure the amount of creep suffered by a test piece (e.g., metalsubstrate), an X-cut must first be made to the test piece, such that theX-cut reaches the base material of the test piece. A cutting knife shallbe used to make the X-cut. The X-cut shall have a cross angle from 60°to 90°. The cutting knife shall be SK2 and have a hardness of HV820+/−30. Verify the X-cut by applying electric current. Immerse thetest piece in 5 wt % NaCl solution at 55° C. in a glass container, andseal the container tightly. After 240 hours, remove the test piece fromthe container, then immediately rinse and wipe it lightly with a softcloth. Check test piece for any rust, blisters or peeling. If rust orblister is found, measure the blister width. Then immediately attach apiece of adhesive tape to the flaw area, and peel it off in the mannerspecified in Adhesion Test (see below). The adhesive tape shall becellophane and be 12 or 24 mm in width (e.g., Nichiban Cellotape). Ifpeeling is found, measure the maximum peeling width, and that should bethe peeling, width. Record either the blister width or the peelingwidth, whichever is larger, as the blister width/peeling width,otherwise known as the creep value (measured in mm).

In certain embodiments, a coating exhibits a creep value according tothe Hot Salt Water Test of about 0.8 mm or less; in certain embodiments,about 0.6 mm or less; in certain embodiments, about 0.4 mm or less; incertain embodiments, about 0.2 mm or less; and in certain embodiments,that is negligible (essentially zero).

B. Adhesion Test

Attach a 12 or 24 mm wide piece of cellophane adhesive tape (e.g.,Nichihan Cellotape) to the coating film surface of a test piececarefully not to leave any bubble between them. Hold one edge of theadhesive tape so that the angle between the adhesive face of the tapeand the test piece is approximately 45° as shown in FIG. 7, and peel thetape off the test piece rapidly in the same direction.

C. Salt Spray Test

The salt spray test can measure the amount of corrosion suffered by ametal substrate by measuring the amount of creep that occurs at thetested area.

To measure the amount of creep suffered by a test piece (e.g., metalsubstrate), an X-cut must first be made to the test piece, such that theX-cut reaches the base material of the test piece. A cutting knife shallbe used to make the X-cut. The X-cut shall have a cross angle from 60°to 90°. The cutting knife shall be SK2 and have a hardness of HV820+/−30. Verify the X-cut by applying electric current. Affix the testpiece on a salt spray tester at 15° to 30° to the vertical line, andsubject it to spraying of 5.0 wt % NaCl solution for 960 hours. The saltspray tester shall conform to ASTM B117 standard. The salt spray testershall have the test conditions as shown in the table below.

Tester operation method Continuous Test chamber 35 ± 1° C. Air saturatortemperature 47 ± 1° C. Relative humidity of test chamber 95 to Sprayingpressure 70 to 180 kPa (0.7 to 1.8 kgf/cm²) Amount of solution collectedfrom 0.85 to 2.0 mL/hour for 80 cm² pH of solution made by spraying 6.5to 7.2

After the subjecting the test piece to the salt spray tester, rinse thetest piece and clear the corrosion product using a sponge or scrubbingcloth. Measure the width of the largest swollen area of the X-cut. Afterleaving the test piece at room temperature for two hours, check the filmpeeling property by attaching a 12 or 24 mm wide adhesive tape (e.g.,Nichiban Cellotape) and peeling it off as specified in Adhesion Testdescribed above. Measure the width of the largest area of the coatingfilm peeled with the tape. Record the width of either the blistered areaor peeled area, whichever is larger, as the creep value (measured inmm).

In certain embodiments, a coating exhibits a creep value according tothe Salt Spray Test of about 1.6 mm or less; in certain embodiments,about 1.3 mm or less; in certain embodiments, about 1.1 mm or less; incertain embodiments, about 1.0 mm or less; and in certain embodiments,about 0.8 mm or less.

EXAMPLES

For the examples provided below, an epoxy-based coating (e.g., filmlayer) having a plurality of carriers (some with corrosion inhibitorsand some without) was applied (baked at 170° C. for 20 minutes) to asteel sample formed from zinc phosphated steel. The coatings wereapplied using a draw down bar method to a thickness of 25 microns. Theepoxy-based coating included a coating base formed from a BPA epoxyresin, isocyanate and methyl isobutyl ketone (MIBK). The carriers havingfilm-forming compounds were formed as microcapsules. The plurality ofmicrocapsule carrier bodies were formed of polyurethane/ureaformaldehyde. The average outer diameter of the film formingmicrocapsules were 5 μm. The carriers having corrosion inhibitors wereformed as microparticles. The plurality of microparticle carrier bodieswere formed of melamine formaldehyde/pentaerythritol tetrakis. Theaverage outer diameter of the corrosion inhibiting microparticles were 1μm. The amount of carrier in each coating was provided as a % wt. of thecoating and was measured on a dry basis. A creep value was measured andrecorded three times using the Hot Salt Water Test and the Salt SprayTest for the comparative and inventive examples, and the average ofthose three trials was provided below in Table 1.

TABLE 1 Amount of carrier in Hot Salt Salt Spray coating Water Test TestCreep Film-Forming (% wt. on a Creep Value Value Coatings Corrosioninhibitor(s) Compound dry basis) (mm) (mm) Comparative None None 0 0.81.7 Example A Comparative None 50/50 Epoxy 5 1.1 1.2 Example B Resin andEthyl Phenyl Acetate Blend Comparative None 50/50 Epoxy 2.5 0.5 1.1Example C Resin and Ethyl Phenyl Acetate Blend Comparative None 50/50Epoxy 1.0 0.2 1.3 Example D Resin and Ethyl Phenyl Acetate BlendComparative None 50/50 Alkyd 5 1.5 1.5 Example E Resin and Ethyl PhenylAcetate Blend Comparative None 50/50 Alkyd 2.5 0.7 1.4 Example F Resinand Ethyl Phenyl Acetate Blend Comparative None 50/50 Alkyd 1.0 0.2 1.1Example G Resin and Ethyl Phenyl Acetate Blend Inventive8-Hydroxyquinoline/2- 50/50 Epoxy 4/1/2.5* negligible 1.2 Example HMercaptobenzothiazole Resin and Ethyl Phenyl Acetate Blend Inventive8-Hydroxyquinoline/2- 50/50 Alkyd 4/1/2.5* negligible 1.2 Example IMercaptobenzothiazole Resin and Ethyl Phenyl Acetate Blend *Indicatesthe individual % wt. for each corrosion inhibitor and film-formingcompound, and total % wt. can be calculated by adding the valuestogether.

As illustrated in Table 1, Comparative Examples AG each exhibited creepvalues according to the Hot Salt Water Test described herein of 0.2 mmor greater. Inventive Examples H and I each exhibited a negligible(essentially zero) creep value according to the Hot Salt Water Testdescribed herein.

Also shown in Table 1, Inventive Examples H and I also maintained creepvalues according to the Salt Spray Test described herein at least as lowas any of the Comparative Examples A-G.

Inventive Examples H and I provide alternatives to traditional coatingsto protect metal substrates, and offer substantial improvements inpreventing or inhibiting corrosion.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

It should be understood that every maximum numerical limitation giventhroughout this specification includes every lower numerical limitation,as if such lower numerical limitations were expressly written herein.Every minimum numerical limitation given throughout this specificationwill include every higher numerical limitation, as if such highernumerical limitations were expressly written herein. Every numericalrange given throughout this specification will include every narrowernumerical range that falls within such broader numerical range, as ifsuch narrower numerical ranges were all expressly written herein.

All documents cited in the Detailed Description are, in relevant part,incorporated herein by reference; the citation of any document is not tobe construed as an admission that it is prior art with respect to thepresent invention. To the extent that any meaning or definition of aterm in this document conflicts with any meaning or definition of thesame term in a document incorporated by reference, the meaning ordefinition assigned to that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A corrosion inhibiting composition comprising: afirst plurality of carriers, each comprising a first carrier body and afilm-forming compound, the first carrier body encapsulating thefilm-forming compound, wherein the first carrier body is formed of afirst degradable material; and a second plurality of carriers, eachcomprising a second carrier body and a first corrosion inhibitor, thesecond carrier body encapsulating the first corrosion inhibitor, thefirst corrosion inhibitor comprising an organic compound including aring structure, wherein the second carrier body is formed of a seconddegradable material comprising a solid binder, wherein the firstplurality of carriers are microcapsules wherein the film-formingcompound is released upon mechanical degradation of the first degradablematerial; and wherein the second plurality of carriers aremicroparticles wherein the first corrosion inhibitor is released fromwithin the second carrier body upon chemical cleavage of the seconddegradable material.
 2. The corrosion inhibiting composition of claim 1,wherein the organic compound comprises a heterocyclic compound.
 3. Thecorrosion inhibiting composition of claim 1, wherein the organiccompound comprises a chelating agent.
 4. The corrosion inhibitingcomposition of claim 2, wherein the heterocyclic compound includes anendocyclic donor atom and an exocyclic donor atom.
 5. The corrosioninhibiting composition of claim 4, wherein the exocyclic donor atom isdirectly bonded to the ring structure of the heterocyclic compound. 6.The corrosion inhibiting composition of claim 4, wherein the exocyclicdonor atom is not directly bonded to the ring structure of heterocycliccompound.
 7. The corrosion inhibiting composition of claim 2, whereinthe heterocyclic compound comprises one or more of2-mercaptobenzothiazole, 2-mercaptobenzimidazole,2-(benzothiazol-2-ylsulfanyl)-succinic acid, 8-hydroxyquinoline,8-hydroxyquinaldine, and any combination thereof.
 8. The corrosioninhibiting composition of claim 1, wherein the first corrosion inhibitorcomprises one or more of a imidazole compound, a triazole compound, apyrazole compound, a thiazole compound, a oxazole compound, an indazolecompound, a quinoline compound, a quinolone compound, derivatives ofeach, and any combination thereof.
 9. The corrosion inhibitingcomposition of claim 1, further comprising a third plurality ofcarriers, each comprising a third carrier body and a second corrosioninhibitor, the third carrier body encapsulating the second corrosioninhibitor, wherein the third carrier body is formed of a thirddegradable material.
 10. The corrosion inhibiting composition of claim9, wherein the second corrosion inhibitor comprises an organic compoundincluding a ring structure.
 11. The corrosion inhibiting composition ofclaim 10, wherein the organic compound comprises a heterocycliccompound.
 12. The corrosion inhibiting composition of claim 9, whereinthe first corrosion inhibitor includes a thiazole compound, an imidazolecompound, or any combination thereof.
 13. The corrosion inhibitingcomposition of claim 12, wherein the first corrosion inhibitor includes2-mercaptobenzothiazole, 2-mercaptobenzimidazole, or any combinationthereof.
 14. The corrosion inhibiting composition of claim 9, whereinthe second corrosion inhibitor includes a quinolone, a quinolonederivative, or any combination thereof.
 15. The corrosion inhibitingcomposition of claim 14, wherein the second corrosion inhibitor is8-hydroxyquinoline, 8-hydroxyquinaldine, or any combination thereof. 16.The corrosion inhibiting composition of claim 1, wherein thefilm-forming compound comprises one or more of clear varnish, urethanes,epoxy resins, siloxane resins, alkyd resins, linseed oil, tung oil,silyl ester, iscocyanates, or combinations thereof.
 17. A coating forinhibiting corrosion on a metal substrate, the coating comprising thecorrosion inhibiting composition of claim 1, wherein the coatingexhibits a creep value of about 0.1 mm or less according to the Hot SaltWater Test.
 18. The coating of claim 16 exhibits a creep value of aboutzero.
 19. A coating for inhibiting corrosion on a metal substrate, thecoating comprising the corrosion inhibiting composition of claim 1,wherein the coating exhibits a creep value of about 1.2 mm or lessaccording to the Salt Spray Test.
 20. The coating of claim 18 exhibits acreep value of about 1.1 mm or less according to the Salt Spray Test.21. A corrosion inhibiting composition comprising: a first pluralitycarriers, each comprising a first carrier body and a film-formingcompound, the first carrier body encapsulating the film-formingcompound, wherein the first carrier body is formed of a first degradablematerial; a second plurality of carriers, each comprising a secondcarrier body and a first corrosion inhibitor, the second carrier bodyencapsulating the first corrosion inhibitor, the first corrosioninhibitor comprising a first organic compound including a ringstructure, wherein the second carrier body is formed of a seconddegradable material; and a third plurality of carriers, each comprisinga third carrier body and a second corrosion inhibitor, the third carrierbody encapsulating the second corrosion inhibitor, the second corrosioninhibitor comprising a second organic compound including a ringstructure, wherein the second corrosion inhibitor is different from thefirst corrosion inhibitor, and wherein the third carrier body is formedof a third degradable material.
 22. The corrosion inhibiting compositionof claim 21, wherein the first plurality of carriers each formmicrocapsules.
 23. The corrosion inhibiting composition of claim 21,wherein the first plurality of carriers and the second plurality ofcarriers each form microparticles.
 24. The corrosion inhibitingcomposition of claim 21, wherein the first corrosion inhibitor includes2-mercaptobenzothiazole, 2-mercaptobenzimidazole, or any combinationthereof.
 25. The corrosion inhibiting composition of claim 21, whereinthe second corrosion inhibitor includes a quinolone, a quinolonederivative, or any combination thereof.
 26. The corrosion inhibitingcomposition of claim 25, wherein the second corrosion inhibitor is8-hydroxyquinoline, 8-hydroxyquinaldine, or any combination thereof. 27.The corrosion inhibiting composition of claim 1, wherein the corrosioninhibitor comprises from about 10% to about 40%, by weight, of thesecond plurality of carriers.
 28. The corrosion inhibiting compositionof claim 27, wherein the corrosion inhibitor comprises from about 15% toabout 35%, by weight, of the second plurality of carriers.
 29. Acorrosion inhibiting composition comprising: a first plurality ofcarriers, each comprising a first carrier body and a film-formingcompound, the first carrier body encapsulating the film-formingcompound, wherein the first carrier body is formed of a first degradablematerial; and a second plurality of carriers, each comprising a secondcarrier body and a first corrosion inhibitor, the second carrier bodyencapsulating the first corrosion inhibitor, the first corrosioninhibitor comprising an organic compound including a ring structure,wherein the second carrier body is formed of a second degradablematerial comprising a solid binder with a cleavable cross-linking agent,wherein the first plurality of carriers are microcapsules wherein thefilm-forming compound is released upon mechanical degradation of thefirst degradable material; and wherein the second plurality of carriersare microparticles wherein the first corrosion inhibitor is releasedfrom within the second carrier body upon chemical cleavage of the seconddegradable material.
 30. The corrosion inhibiting composition of claim1, wherein the first corrosion inhibitor is a solid.
 31. The corrosioninhibiting composition of claim 21, wherein at least one of the firstcorrosion inhibitor and the second corrosion inhibitor is a solid. 32.The corrosion inhibiting composition of claim 29, wherein the firstcorrosion inhibitor is a solid.